Application of wood veneer to a contoured base



Nov. 11, 1910 R, H, LEw s 3,541,592

APPLICATION OF WOOD VENEER TO A CONTOURED BASE Filed Oct. 9, 1967 lllllIHi II 'I l l.l.lll m INVENTOR. RAYMOND H. LEWIS ATTORNEY United StatesPatent 3,541,592 APPLICATION OF WOOD VENEER TO A CONTOURED BASE RaymondH. Lewis, Fort Lauderdale, Fla., assignor to Roberts ConsolidatedIndustries, Inc., City of Industry,

Calif., a corporation of California Filed Oct. 9, 1967, Ser. No. 677,495Int. Cl. B27d 1/00 US. Cl. 144-315 2 Claims ABSTRACT OF THE DISCLOSUREThis invention relates to a means and method for conditioning woodveneer whereby a degree of flexibility is imparted thereto suflicientfor its self-conformation to one or more non-planar faces of a base towhich it is permanently united. It involves means (1) for initiallybreaking down the grain configuration of the wood and/ or disrupting itsfibrous structure, without noticeable damage thereto or change in itsappearance and, when initially afiixed to the base, (2) vapor heating ofsuch conditioned areas whereby to facilitate bending thereof to coverone or more contoured faces of the base in exact conformity therewithand to unite thereto at every point over their mutually contactingsurfaces.

Wood veneer is commonly produced with a standard thickness of about Aready tendency to crack or split requires that it be handled carefully.It is also difficult to apply such a veneer to any contoured basebecause of insuflicient flexibility in its body structure. Althoughveneered furniture is attractive and greatly in demand, application ofthe veneer is generally confined to relatively flat surfaces thereof.Use of the finer woods, such as walnut, cherry, maple, rosewood, etc.,is attended with all these difficulties. It is accordingly a primaryobjective of this invention to provide a means and method whereby tocondition veneers of diverse woods (1) for facile bending and (2) forexpeditious application of such conditioned veneers to their permanentbases with exact conformation to one or more non-planar faces thereof.The furniture industry is but one market for this invention. Otherproducts to benefit therefrom are frames for pictures and mirrors,mouldings, building interior trim, cabinet doors, stair rails, etc.

Further objects and advantages residing in the present invention relateto its adaptability to veneers of different woods some of which havecommonly been rejected as too difficult for assembly with contouredbases; to expeditious handling and treatment of wood veneers through theinitial and subsequent stages of conditioning and application; and touse of such veneers on non-planar faces of bases where bending isrequired beyond the normal capacity of any veneer, thereby avoiding itsspoilage and rejection.

These and other objects of this invention will appear more fully fromthe detailed description to follow wherein reference is made to theaccompanying drawing exhibiting a suggestive embodiment of means andsteps suitable for employment of the invention. In the drawing:

FIG. 1 is a front elevational view of the framework 3,541,592 PatentedNov. 17, 1970 which encloses and mounts a pair of rollers, oneadjustable toward and from the other to vary the clearance therebetween,the framework front wall being broken away to exhibit portions of thetwo rollers, also the bearings therefor;

FIG. 2 is a vertical sectional view, taken on line 22 of FIG. 1, showingin elevation the inside face of the divided framewonk end wall, togetherwith the bearings carried thereby, but omitting the roller shaftstherefrom;

FIG. 3 is an enlarged schematic view showing a piece of veneer inoperative position between the two rollers;

FIG. 4 is an enlarged fragmentary section, taken on line 4-4 of FIG. 3;

FIG. 5 is an enlarged fragmentary plan view of one end portion of apiece of veneer as it appears when conditioned;

FIG. 6 is an enlarged end elevation of the veneer piece as it appearsafter leaving the rollers; and

FIGS. 7-11 are schematic views showing the veneer and its base duringsuccessive stages of application of the former to the latter.

The work to be operated upon, according to this invention, consists ofan elongated wood veneer piece V and an elongated base C of wood,plywood, chipboard, or other suitable material. Such a base is known asa core, and will be so referred to herein. In cross section the core issubstantially uniform from end to end, its length running up to perhaps16 feet or so. Its cross sectional contour, also uniform throughout itslength, is usually such as to provide an attractive design, and mayinvolve one or more faces, with curves convex and/or concave, connectedby variously rounded corners, depending largely upon the use for whichthe finished product is intended. The veneer piece, by contrast, isrelatively flat and inflexible, its length is usually coterminous withthat of the core, and its form is generally that of a strip elongated inthe direction of its grain structure. The strip width desirably is suchas to cover one or more selected faces of the core when flexibilized andwrapped therearound in response to a bending operation.

Obviously a piece of normally-inflexible wood veneer presents a problemwhen efforts are made to bend it closely around and into exactconformity with one or more faces of a core preparatory to itsinseparable bonding therewith. As a first step, the veneer strip must beconditioned for bending; then the faces of the strip and core which areto confront each other should receive a spread of adhesive; then thestrip, still flat, is adhesively afiixed to one of the core faces; then,while so assembled, the strip and core are advanced together lengthwiseadjacent to and/or between a multiplicity of agencies which subject thestrip briefly to vapor-heating confined to the area to be bent and thento pressure forces which bend the veneer strip around and down upon theface or faces of the core which are to be covered thereby; and finallyan evenly distributed and continuing pressure is directed against thestrip for a time sufficient to conform it closely to the confrontingcontoured face or faces of the core and to induce its bonding therewith.In a general way, this is the present mode of operation involved in theapplication of relatively inflexible wood veneer strips to cores whichmay be variously contoured on one or more of their faces. A suggestivemechanism for thus applying conditioned veneer strips to cores ofdiverse designs is disclosed in the Bechtold Pat. No. 3,296,056 of Jan.3, 1967, but only when importantly modified as hereinafter noted.

The means and method of this invention comprise (l) the conditioningunit of FIGS. 1-4 and (2) the bending steps outlined in FIGS. 7-11.These two stages in the method may be performed separately, eachindependent of the other, or the means therefor may be combined into asingle mechanism. Each strip of wood veneer V of a desired width isinitially passed through the rollers of the conditioning unit.Thereafter it is stacked along with other similarly conditioned woodveneer pieces, awaiting further treatment by the bending unit at aconvenient time; or, alternatively, each such veneer strip, upondelivery from the conditioning unit, may immedately be operated upon bythe several instrumentalities comprised in the bending unit. With thesepreliminary observations, the conditioning unit of FIGS. l4 will now bedescribed.

A sturdy type of machine is used, placed desirably between the ends oftwo tables arranged in tandem (not shown), one for holding a supply ofveneer pieces ready for conditioning, and the other for accommodatingsuch pieces after conditioning. A stout stand having a top 15 fixedlysupports an enclosing framework comprising an upstanling end wall 16opposite a two-part end wall formed of upper and lower plates 17 and 18spaced slightly apart to leave a gap 19 therebetween. The end walls arefixedly joined, as by bolts 20, to opposite ends of upstanding elongatedfront and rear walls 21 and 22, respectively. Between the end walls isextended a pair of horizontal rollers U and L, one above the other witha very slight potential clearance therebetween that is aligned with thegap 19 in one end wall. The front and rear walls are each provided witha horizontal slot 23 in line with the gap 19 and extending awaytherefrom for the major portion of the lengths of the two rollers U andL.

The lower roller L is mounted fast upon a shaft 25 which is rotatablysupported at opposite ends within bearing blocks 26, one atfixed to eachend wall 16 and 18. Similarly the upper roller U is carried upon a shaft27 whose opposite ends are mounted in bearing blocks 28, one atfixed toeach end wall 16 and 17. A sprocket 'wheel 29 is mounted fast on theshaft 25 near one end thereof to receive thereover a chain 30 adapted tobe driven from a reduction gear 31 to which power is transmitted from amotor M. The lower bearing blocks 26 are fixedly anchored in place withthe aid of bolts 32 which traverse the walls 16 and 18 for threadedengagement with the blocks. A bottom support for each bearing block isalso provided in the form of a bar 35 in engagement with its under face;a substantial part of this bar is closely fitted within a recess 36which is extended horizontally across the end wall to which it isconnected as by bolts 37. Since this bar abuts the lower face of therecess and also the bearing block thereabove-both confronting faceslying in a horizontal planea very substantial vertical support for thelatter is provided. Without this abutment bar, the bolts 32 would tendto shear off in response to the tremendous pressure generated.

The upper bearing blocks 28 are very slightly vertically adjustable. Asby bolts 41 traversing the walls 16 and 17 and vertically-elongatedslots 42 in the blocks, provision for slight vertical movement is made.Overlying the upper face of each of these blocks are horizontallyelongated wedge blocks 45 and 46, the former being the upper one. Bolts47 are extended through this block and the proximate end walls tofixedly secure the upper wedge block 45 in place. The lower wedge block46, however, is mounted for sliding movement in a horizontal direction,thereby to shift its body vertically whenever its beveled face isadvanced along the similar face of the upper wedge block. A support foreach lower Wedge block which permits such limited movements to takeplaceis provided by bolts 50 which are anchored in the end walls 16 and 17 toextend therefrom through oblique slots 51 formed in the block 46. Thelower wedge block rests upon the upper face of the proximate bearingblock 28 to exert a variable pressure thereupon. To pr0-' vide a fixedabutment for each upper wedge block whereby it may resist verticalmovement in response to great upward pressures transmitted from thewedge block therebelow, I provide an enclosing recess 54 wherein asubstantial portion of both blocks 45 and 46 may be fitted. Each recessis extended horizontally across the end wall 16 or 17, as the case maybe, its upper face abutting the top face of the upper block 45.Operation of the moveable wedge block is facilitated by a bolt 57 inrotatable connection therewith and extended through the front wall 21with which it is in threaded engagement. A lock nut 58 fitted upon thebolt is adapted to engage with the front wall with varying degrees offriction, depending upon its adjusted position. It will be noted thatthe uppermost vertical position of the upper roller U is fixed inresponse to rotation of the operating bolt 57 working through the wedgeblocks 45 and 46; also that the wedge blocks, being partly enclosedwithin the end walls, serve as horizontal abutments which are adjustableto effectively prevent any upward movement of the upper roller U beyonda selectively fixed point, thereby limiting its clearance with the lowerroller L.

The maximum spacing at the nip between the rollers is somewhat less thanthe thickness of the veneer pieces to be passed therethrough. Assumingthe veneer thickness to be about .O31"-.032", the operating clearancebetween the rollers U and L should be adjusted to about .017", or nearlyone-half the thickness of the veneer (FIG. 3). The surface of the lowerroller is specially formed to provide a multitude of closely spacedprojections capable of pressing into the body of the wood to producetherein indentations which have the effect of breaking down its grainconfiguration and/ or disrupting its fibrous structure. As a result,resistance to bending of the veneer around axes parallel with its grainis somewhat reduced, although its body is still generally inflexible. Asa simple form of projections suitable for the lower roller L,circumferential scorings are quite effective. A desirable spacing of thescore lines s (see FIG. 4) is .030", with uniform depths therebetween of.010". A single pass between the rollers requires that the veneer yieldmomentarily to the clearance provided thereat, viz., .017", but withemergence from between the rollers the veneer tends to expand to about.029" (FIG. 6). The effect upon the fibrous structure of the veneerbody, resulting from the pressure forces transmitted momentarily to itsunder face, is primarily to condition it for subsequent flexibilization.A return to substantially its normal thickness tends to follow, but thisis unimportant. It is important, however, that the pressure forces atthe nip of the rollers be very considerable, ranging perhaps from 30 to50 tons p.s.i. The upper roller U, it will be noted, is free to occupy avery slightly lower position when not in use. At such times it may evenrest upon the lower roller with no clearance therebetween. Advance of aveneer piece into the nip between the-rollers forces the upper roller tomove upwardly as far as permitted by adjustment of the wedge block 46.This adjustment may be very fine, thereby controlling accurately thedegree of compressive forces exerted. There is no lost motion or playbetween the adjusting components involved-an important consideration ifgeneration of desired compressive forces is to be achieved withprecision.

To operate dependably and with a wide safety margin where pressures ofmany tons are involved, it is necessary that the four walls enclosingthe rollers provide mountings therefor that are strong and heavy. Forthis purpose, steel plates of approximately 1 /2 in thickness aresuggested. Particularly is more than usual strength required for such aroller framework because of the horizontal slots 23 and gaps 19 providedin the front and rear walls and at one end thereof for a specialpurpose. This is to permit accommodation between the rollers of veneerpieces whose widths may vary widely-from less than 6" be conditioned bythe rollers in one pass. Wider veneer up to perhaps 2 feet or more.Assuming a length for each roller of 1 foot, any veneer piece up to thatwidth can pieces can also be operated upon, the rollers optionallyconfining their engagement with the veneer to one sideportion thereof ina first pass and to an opposite sides portion in a second pass.Furthermore, it is possible to run a wide veneer piece through therollers when only a single edge portion thereof is to be conditioned. Insuch a case, a major portion of the veneer piece would not be engaged bythe rollers, but would remain outside the housing beyond the gap 19 inone end wall. These are some of several advantages to be derived fromuse of compressor rollers whose clearance is extended out through theslots and gap of the framework walls permitting veneer pieces of varyingWidths to be moved in, out, and through the machine as circumstances mayrequire from time to time.

The veneer pieces, when conditioned as above described, are ready toenter the second stage of the present method. This involvs first anapplication of a spread of suitable adhesive to the raw face of theveneer pieces. Desirably this is a contact adhesive which may beconveniently applied in the form of a spray. The adhesive spread a soapplied adds considerable strength to the veneer. It is not necessarythat the adhesive be as completely dry as when applied to a plasticmaterial, since the porous character of thin wood veneer promotes escapeof the volatile solvents from the adhesive. A similar spread b ofadhesive is also applied to each face of the core which is to be coveredby the veneer in the operation of bending. With the adhesive spreads soapplied, the wood veneer, still relatively flat, is then indexed to thecore. This adhesive union between the veneer and core is initiallyconfined to a relatively narrow band extending the full length of thework which is then ready to be advanced lengthwise through a bendingmachine whose essentials will now be described.

A plurality of aligned knurled rollers 59 interconnected for rotation inunison provides a moving support for the work when rested thereon asindicated in FIGS. 7l1. The cross sectional contour of the core may welldetermine whether the work shall be positioned with the veneer down orup during its movement through the machine. The simple contour of thecore, which is shown in these figures as that of a plain rail, makes itadvantageous that the work proceed through the machine with the veneeron the down face of the core (FIG. 7). Its movement through the machineis continuous, one piece of work following closely upon another, whenhand-laid in operative positions by experienced workmen.

The first agency to operate upon the work is a heat applying means. Theheat transmitted to a veneer of wood must be applied uniformly and withcare, otherwise the veneer will tend to become brittle rather thanflexible. To meet this problem, the heat is delivered in the form ofvapor into the path of movment of the work at a point proximate to itsraw face. For his purpose, an electricallyoperated vapor generating unit60 may be utilized, with a short pipe line 61 therefrom terminating in aplurality of spray jets or nozzles 62 proximate to the raw face of theveneer. The vapor discharged from these jets forms a stationary cloudthrough which the work is advanced during a time interval suflicient forsafe and effective heating of the veneer and without noticeable increasein its moisture content. A speed of as much as feet per minute foradvance of the work is permissible. As an example, the vapor may besteam generated from water at approximately 40 pounds p.s.i., this beinga temperature of close to 350 degrees F., and relatively dry.

This high pressure application of vapor disrupts the cellulose structurein the veneer which then becomes flexibilized to permit promptsubsequent bending through a curve having a radius as short as A In thiscrucial step of applying vapor heat to condition wood veneer,

this invention marks a distinct advance in the art. The

bending machine itself need not be essentially different from thatdisclosed in the Bechtold Pat. No. 3,296,056

already mentioned, except for the heating unit. Here a different type ofheat must be employed to meet the special problems posed by wood veneer,and the use of controlled heat which is transmitted through vaporparticles has proved an adequate solution.

FIGS. 8-11 indicate schematically some essential steps through which thework proceeds in the bending operation. After heating, opposite freeportions of the oncoming veneer are engaged by certain stationary hollowcam shoes 63 angled to gradually deflect these portions of the veneertoward the sides of the core while a hold down roller 64 engages its top(FIG. 8). The chamber within each shoe is in communication through apipe 65 with the vapor-generating unit 60. Jet openings (not shown)confronting the shoe-engaged faces of the veneer are also providedwhereby to release vapor therethrough for discharge against the rawsurfaces of the engaged veneer piece. The heat is thus carried to thevery point at which the veneer is constrained to execute a bend througha curve of relatively short radius to assure against failure in thisdelicate operation.

Other rollers 69 thereafter engage the on-coming veneer portions sodeflected by the cam shoes, to advance such portions into firmengagement with the opposite sides of the core, leaving free endportions extending thereabove (FIG. 9), then other cam shoes 70, similarto the shoes 63 and in communication with a source of vapor, engage thefree end portions upstanding above the core while discharging vaporthereagainst, to deflect them downwardly toward the core top (FIG. 10),and finally these free end portions so deflected are pressed down byother top rollers 71 into firm engagement with the core top (FIG. 11).These several operating agencies may involve multiple rollers atsuccessive points lengthwise of the machine, also other rollers havingspecial profiles to assure conformation of the veneer with anynon-planar contours present in the core design. The positions of thesevarious instrumentalities remain stationary, while the work is inconstant motion to be acted upon successively by these agencies, therebyassuring successful bending of the wood veneer pieces after beingpreviously conditioned and heated, as herein described.

It is to be noted that the surface of the veneer is not cut during itspassage through the rollers U and L. The profile of the score lines s(FIG. 4) which are impressed upon one face of the veneer is such as toavoid duplication of those scores upon its opposite face. Rather, therelatively shallow depths between the tops of the scores are so designedas to compress the veneer body linearly with the end in view ofdisrupting its fibrous structure, but leaving it otherwise undamaged.The unyielding smooth face of the upper roller U which backs up theveneer when linear compression takes place affords full protection toits opposite face Whose appearance remains unaffected. The preliminaryconditioning, when followed by vapor heating, imparts a degree offlexibilization to the veneer which permits it to execute bends throughcurves of short radius. Each such bend may proceed about a single axisor several axes, and involve a single radius or more than one, dependingupon the core contours to which the veneer must be conformed. By themeans herein disclosed, these operations of conditioning the veneer andapplying it to a core may be performed dependably and expeditiously,thus assuring volume production at a minimum cost.

I claim:

1. The method of conditioning wood veneer in the form of an elongatedstrip having the lay of its grain parallel therewith, whereinsubstantial pressure forces are applied along closely spaced linesextending lengthwise of the strip, and wherein the strip is adhesivelyassembled with a core of substantially the same length, followed bysubjecting the pressure-treated area of the strip to vapor heat toproduce flexibilization thereof, and applying pressure forces toflexibilized areas of the veneer to induce a bending thereof around andupon selected faces of the core for permanent union therewith.

2. The method of conditioning wood veneer in the form of an elongatedstrip having the lay of its grain parallel therewith, whereinsubstantial pressure forces are applied along closely spaced linesextending lengthwise of the strip, and wherein the strip is adhesivelyassembled with a core of substantially the same length, followed bysubjecting the pressure-treated area of the strip to vapor heat toproduce fiexibilization thereof, and applying pressure forces tofiexibilized areas of the veneer to induce a bonding thereof around andupon selected faces of the core for permanent union therewithconcurrently with the application of vapor heat to the veneer atselected bending points thereof.

References Cited UNITED STATES PATENTS Pine 144327 Grimstad 144-314 Munz1443l5 Hanemann 144-327 Elmendorf 144-327 Bechtold 156212 Bechtold156-2l2 GERALD A. DOST, Primary Examiner US. Cl. X.R.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent 3,541,592Dated November 17, 1970 InVentor(s) Raymond H Lewis It is certified thaterror appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

Column 3, line 18, "upstanling" should read upstandin Column 4, line 73,cancel "be conditioned by the rollers one pass. Wider veneer" and insertthe same after "width can" in line 75, same column 4.

Signed and sealed this 13th day of April 1971.

(SEAL) Attest:

EDWARD M. FLETCHER,JR. WILLIAM E SCHUYLER, Attesting OfficerCommissioner of Paten

